NAME

       Crypt::AuthEnc::CCM - Authenticated encryption in CCM mode

SYNOPSIS

        ### OO interface
        use Crypt::AuthEnc::CCM;

        # encrypt and authenticate
        my $ae = Crypt::AuthEnc::CCM->new("AES", $key, $iv, $adata, $tag_len, $pt_len);
        my $ct = $ae->encrypt_add('data1');
        $ct .= $ae->encrypt_add('data2');
        $ct .= $ae->encrypt_add('data3');
        my $tag = $ae->encrypt_done();

        # decrypt and verify
        my $ae = Crypt::AuthEnc::CCM->new("AES", $key, $iv, $adata, $tag_len, $pt_len);
        my $pt = $ae->decrypt_add('ciphertext1');
        $pt .= $ae->decrypt_add('ciphertext2');
        $pt .= $ae->decrypt_add('ciphertext3');
        my $tag = $ae->decrypt_done();
        die "decrypt failed" unless $tag eq $expected_tag;

        #or
        my $result = $ae->decrypt_done($expected_tag); # 0 or 1

        ### functional interface
        use Crypt::AuthEnc::CCM qw(ccm_encrypt_authenticate ccm_decrypt_verify);

        ($ciphertext, $tag) = ccm_encrypt_authenticate('AES', $key, $nonce, $adata, $tag_len, $plaintext);
        $plaintext = ccm_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext, $tag);

DESCRIPTION

       CCM is a encrypt+authenticate mode that is centered around using AES (or any 16-byte
       cipher) as a primitive.  Unlike EAX and OCB mode, it is only meant for packet mode where
       the length of the input is known in advance.

EXPORT

       Nothing is exported by default.

       You can export selected functions:

        use Crypt::AuthEnc::CCM qw(ccm_encrypt_authenticate ccm_decrypt_verify);

FUNCTIONS

   ccm_encrypt_authenticate
        my ($ciphertext, $tag) = ccm_encrypt_authenticate($cipher, $key, $nonce, $adata, $tag_len, $plaintext);

        # $cipher .. 'AES' or name of any other cipher with 16-byte block len
        # $key ..... key of proper length (e.g. 128/192/256bits for AES)
        # $nonce ... unique nonce/salt (no need to keep it secret)
        # $adata ... additional authenticated data
        # $tag_len . required length of output tag

       CCM parameters should follow
       <http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38c.pdf>

        # tag length:   4, 6, 8, 10, 12, 14, 16 (reasonable minimum is 8)
        # nonce length: 7, 8, 9, 10, 11, 12, 13 (if you are not sure, use 11)
        # BEWARE nonce length determines max. enc/dec data size: max_data_size = 2^(8*(15-nonce_len))

   ccm_decrypt_verify
        my $plaintext = ccm_decrypt_verify($cipher, $key, $nonce, $adata, $ciphertext, $tag);
        # on error returns undef

METHODS

   new
        my $ae = Crypt::AuthEnc::CCM->new($cipher, $key, $nonce, $adata, $tag_len, $pt_len);

        # $cipher .. 'AES' or name of any other cipher with 16-byte block len
        # $key ..... key of proper length (e.g. 128/192/256bits for AES)
        # $nonce ... unique nonce/salt (no need to keep it secret)
        # $adata ... additional authenticated data
        # $tag_len . required length of output tag
        # $pt_len .. expected length of plaintext/ciphertext to encrypt/decrypt

   encrypt_add
        $ciphertext = $ae->encrypt_add($data);        # can be called multiple times

   encrypt_done
        my $tag = $ae->encrypt_done;                  # returns $tag value

   decrypt_add
        $plaintext = $ae->decrypt_add($ciphertext);   # can be called multiple times

   decrypt_done
        my $tag = $ae->decrypt_done;           # returns $tag value
        #or
        my $result = $ae->decrypt_done($tag);  # returns 1 (success) or 0 (failure)

   clone
        my $ae_new = $ae->clone;

SEE ALSO

       •   CryptX, Crypt::AuthEnc::EAX, Crypt::AuthEnc::GCM, Crypt::AuthEnc::OCB

       •   <https://en.wikipedia.org/wiki/CCM_mode>